Bump trillian-opensource-ci/db_server from `4569876` to `97d822e` in /config/trillian/mysql #1567

Job	Run time
Test github action with TUF (v1.27.x, main, 1.23.x, test github action with TUF)	4m 38s
Test github action with TUF (v1.28.x, main, 1.23.x, test github action with TUF)	4m 16s
Test github action with TUF (v1.29.x, main, 1.23.x, test github action with TUF)	4m 36s
Test github action with TUF (v1.30.x, main, 1.23.x, test github action with TUF)	4m 23s
	17m 53s

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